In the customary installation an entrance door is hinged in a doorway and swings inwardly when the door is unlocked. The doorway is defined by a frame mounted in the wall of the building. The vertical portion of the frame near the edge of the door is known as the jamb. The locking mechanism for the door is usually mounted on the door and includes a bolt which engages in a socket in the jamb for locking the door.
A burglar intent upon breaking and entering the building can often forcefully kick against the door near the lock. The result of such a powerful inward thrust against the margin of the door is often to tear the lock mechanism away from its mounting on the door or to tear the bolt through the socket in the jamb or partially to tear both lock mounting and bolt socket sufficiently that the entrance door is allowed to swing inwardly to admit the burglar.
If the burglar is concerned about detection resulting from the crashing, bursting sound resulting from the first approach, a second approach is to pry the margin of the door and the jamb away from each other sufficiently far that the end of the bolt barely clears the socket in the jamb for allowing the door to swing inwardly. There are portable, battery-operated electric drills which are relatively quiet in operation. The burglar drills a hole through the doorstop at the very edge of the door immediately adjacent to the jamb on the opposite side from the hinges. The end of a prying tool is inserted into this hole between the jamb and the edge of the door. The prying tool provides a tremendous mechanical advantage through which the burglar can force the edge of the door and the jamb sufficiently far apart that the bolt no longer reaches into the socket. The door can now be swung open almost noiselessly.